The invention relates generally to hitching members for connecting a towed vehicle with a towing vehicle, and more particularly to an improved self-locking telescoping towing arm for use as part of a tow bar assembly.
Tow bar assemblies for use as hitching members are common in the art. These assemblies generally use two towing arms which are coupled between a towing vehicle and a towed vehicle. It is desirable to be able to store tow bar assembly. To this end, tow bar assemblies with collapsible arms have been suggested. This allows the towing arms to fit in a smaller space when not in use. Therefore, these towing arms are generally movable between a collapsed storage position, and an extended towing position. They must be provided with some means for locking the arms in the extended position to hold the towed vehicle at a substantially constant distance from the towing vehicle during towing.
It has been shown in the prior art to use a telescoping towing arm having an inner leg and an outer leg in a tow bar assembly, as for example in U.S. Pat. No. 5,356,166, in order to accomplish the collapsible feature of the towing arms to allow for storage. However, the prior art telescoping towing arms have utilized locking mechanisms with spherical catches and a groove that entirely encircles the inner leg of the telescoping arm. Because the groove completely encircles the inner leg, it can weaken the inner leg significantly. Obviously a stronger leg is desired over a weaker leg because of the danger and expense involved if a towing leg should break.
Often it is necessary, or at least recommended, to disassemble the towing arms for routine cleaning or lubricating of the parts. It may also be necessary to disassemble the towing arms to inspect the parts or to replace any damaged parts. For this reason, towing arms that can be disassembled and reassembled easily are desirable.
Because the spherical catches contact only a small portion of the groove, several catches are needed in order to lock the arms securely in the extended position. This leads to increased manufacturing and assembly costs. Because there are several spherical catches, they are difficult to keep track of during disassembly for maintenance. Furthermore, because of their shape they tend to roll away if dropped on the floor.
The difficulties encountered in the prior art and discussed above are substantially eliminated by the present invention.